Production and characterization of low molecular weight heparosan in Bacillus megaterium using Escherichia coli K5 glycosyltransferases.

Low molecular weight heparosan is an un-sulfated polysaccharide primarily used as a precursor for heparin synthesis that has recently been used in drug delivery applications. Heparosan synthesis from recombinant bacterial systems provides a safer alternative to naturally producing pathogenic bacterial systems. In this study, we engineered a functional heparosan synthesis pathway in Bacillus megaterium by the expression of E. coli K5 kfiC and kfiA glycosyltransferase genes. Upregulation of individual UDP-sugar precursor pathway genes enhanced the heparosan production, indicating that UDP-precursor sugar concentrations were limiting the biosynthesis. The engineered B. megaterium yielded a maximum heparosan concentration of 394 mg/L in batch bioreactor. The heparosan titer was further increased to 1.32 g/L in fed-batch fermentation. Nuclear magnetic resonance analysis revealed that the chemical structure of B. megaterium derived heparosan was identical to E. coli K5 heparosan. The heparosan molecular weight varied from 31 to 60 kDa, indicating its potential as a precursor for chemoenzymatic heparin biosynthesis. This study provides an efficient process to produce heparosan from non-pathogenic B. megaterium.

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Déclaration de conflit d'intérêts

Declaration of competing interest The authors (Ganesh Nehru, Subbi Rami Reddy Tadi, and Senthilkumar Sivaprakasam) declare the following competing financial interest(s): Indian patent application filed for the “Recombinant Bacillus megaterium for production of heparin precursors” (Patent Application No. 201831017897). Other authors declare no competing interests.